"Which of the following statements are true?

Wood, plastic, rubber and air are good insulators because A. they conduct charge. B. charge flows easily. C. they don’t have fre

Julli [10]

C. They don't have free electrons.
The only things capable of conducting a charge are things that have charged particles in them that are free to move, e.g free electrons, free positions, or dissociated ions

6 0

3 years ago

an object has a mass of 50kg, a final height of 20m and an initial height of 8m. what is the amount of work done

Andrei [34K]

amount of work done is 5880 J

Given:

mass of object = 50kg

Final height = 20m

initial height = 8m

To Find:

amount of work done

Solution:

work is done when a force acts upon an object to cause a displacement. You can calculate the energy transferred, or work done, by multiplying the force by the distance moved in the direction of the force.

The work done by gravity is given by the formula,

W = mgh

W = 50 x 9.8 x ( 20-8)

= 5880 J

So the work done is 5880 J

Learn more about Work done here:

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7 0

2 years ago

A 3.53-g sample of aluminum completely reacts with oxygen to form 6.67 g of aluminum oxide. find percent composition

katrin2010 [14]

The mass percent composition of aluminum is 52.9% in aluminum oxide.

Mass of the aluminum = 3.53 g

Mass of the aluminum oxide = 6.67 g.

The mass percent of a substance is the mass of the substance divided by the mass of the compound into 100.

Aluminum reacts with oxygen to form aluminum oxide.

The overall balanced equation for the reaction is,

$Aluminum + Oxygen→Aluminum \: oxygen$

$4Al +3O _{2}→2Al _{2}O _{3}$

The mass percent composition of aluminum in the aluminum oxide is,

$Mass \: percent = \frac{ Mass \: of \: the \: substance}{ Mass \: of \: the \: compound} \times 100$

$Mass \: percent = \frac{Mass \: of \: the \: aluminum}{ Mass \: of \: the \: aluminum \: oxide } \times 100$

$Mass \: percent = \frac{3.53}{6.67 } \times 100$

= 52.9 %

Therefore, the mass percent composition of aluminum is 52.9% in aluminum oxide.

To know more about aluminum oxide, refer to the below link:

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7 0

2 years ago

After three half-lives, one-ninth of an original radioactive parent isotope remains, and eight-ninths has decayed into the daugh

BartSMP [9]

Answer:

B. False

The true statement will be:

After three half-lives, one-eighth of an original radioactive parent isotope remains, and seven-eighth has decayed into daughter isotopes.

Explanation:

Half life means the time after which the amount of the given substance becomes half of its initial amount, by radiation.

Thus after each successive half life the material is halved or half of it is decayed, which leads to a general formula:

Remaining Amount = 1/2^n of parent isotope

where, n is the number of half lives passed. So, for three half-lives:

Remaining Amount = 1/2^3 of parent isotope

Remaining Amount = 1/8 of parent isotope

Thus, the decayed amount will be:

Decayed Amount = (1-1/8) of parent isotope

Decayed Amount = 7/8 of parent isotope

Thus, the given statement is B.False

8 0

3 years ago

After a collision, the y-component of momentum of a car is 4.50 meters/second, and the x-component of its momentum is 9.80 meter

Natalka [10]

The components are at a right angle so the resultant is R^2 = 4.50^2 + 9.80^2 R = 10.78 or 10.8

Hope this helps!!
~Lena~

5 0

3 years ago